A straight metal rod is oriented east–west and slides northward at constant speed on a pair of horizontal rails. A uniform magnetic field points vertically upward. Which statement correctly describes the resulting charge separation along the rod?
(a) The east end becomes negatively charged and the west end becomes positively charged.
(b) The leading (north) edge of the rod becomes positively charged while the trailing (south) edge becomes negatively charged.
(c) The east end becomes positively charged and the west end becomes negatively charged.
(d) No charge separation occurs because the rod moves parallel to the magnetic field.